1. Field of the Invention
This invention relates to a device for connecting wires. More particularly, this invention relates to a device for connecting wires, known as tracer wires, placed near buried utilities, such as plastic natural gas pipes, for the purpose of locating these utilities.
2. Description of Related Art
Pipes buried below the surface of the earth require periodic service and/or repair. Damaged pipes must be located and excavated in order to receive such service. Location of underground pipes is a traditionally difficult task, especially in areas containing large networks of underground pipes, wires and other buried objects. In addition, it is preferred that methods employed in locating buried utilities operate from above ground and that they not require prior knowledge of the location of, or access to, the utility to introduce special signals for detection.
Underground pipelines are generally constructed of either metal or, commonly, plastic such as polyethylene and polyvinyl chloride. Plastic is a preferred pipe material because it is durable, inexpensive, lightweight, inert, easy to manufacture and easy to install. However, in the absence of some detection means associated therewith, plastic pipe is virtually undetectable with traditional underground pipeline location methods.
One means for addressing the problem of locating non-electrically conductive, non-magnetic buried utilities is the use of tracer wires which run along the buried utility and are installed when the utility distribution network is being constructed or when a new service connection is being added to an existing network. When a new service is added to an existing network, the tracer wire associated with the new service, referred to herein as a branch wire, must be connected to the tracer wire, i.e. primary tracer wire, running along the main buried utility. Such tracer wire connections are currently made either by using a standard insulation-displacement connector and then applying environmental insulation to the assembled connector and wires, or by using direct burial connectors that are designed, in general, for other applications. All currently used connectors are applied manually and the connection cannot be made remotely, such as in a keyhole.
To be suitable for use with underground utilities, direct bury tracer wire connectors must be able to provide a reliable electrical connection between the main tracer wire and the branch wire, must have adequate mechanical strength, must be environmentally sealed, must be economical to manufacture, and must be easy to apply. In addition, because new service connections are sometimes made using small size excavations, i.e. keyholes, it should be possible to apply the connector using a simple, remotely operated tool.
There exist at the present time numerous tap connectors on the market that allow for the connection of a branch wire to a running trace wire without cutting the running wire or stripping the insulation from the wire. Examples of such products include SCOTCHLOK® tap connectors from 3M Corporation and ELECTRO-TAP® connectors from AMP/TYCO. However, these connectors are generally not environmentally protected. Selected models are available pre-filled with silicone grease, but the design of the connectors does not assure reliable protection against environmental factors. In addition, the connector application is performed in several steps that require multiple tools and considerable manual dexterity of the person using the connector.
Insulation piercing connectors, such as the KZ-series from TYCO Electronics, are also known. Although intended for direct burial, these connectors are designed for high voltage and high current carrying capacity and their wire gage ranges are not suitable for use as tracer wires. Because the connectors require hand tools and proper alignment of the connectors and the tracer wires during installation, remote installation would be difficult, if not impossible. In addition, insulation piercing connectors are relatively expensive.
Yet another type of known connector is the DRYCONN® direct bury lug from King Innovations, St. Charles, Mo. This is the only commercial connector known to us that is suitable for use with tracer wires. It is environmentally sealed and relatively inexpensive. However, both the branch wire and the main tracer wire need to be stripped prior to installation. In addition, the wires are secured in the connector block by tightening two small screws. Thus, the connector can only be applied manually, i.e. it is not suitable for remote applications.